Scientists report the experimental results of studying the response characteristics in a millimeter wave band whispering gallery mode sapphire resonator to single-layer graphene at different distances of graphene from the resonator. They found that the evanescent field of the resonance system is extremely sensitive to the environment, surrounding materials and disk coatings. A series of experiments showed that such whispering gallery mode resonance can be used to detect the conductivity and thickness of the materials deposited on top and/or can even be used for advanced biosensing.